Because of the unique characteristics of GNNs,
they are gaining popularity in solving different types of power system problems.
In the context of transmission system SE, [1]} combined a Gauss-Newton solver with a GNN model to perform SE using only SCADA data.
Ref. [2]} performed GNN-based SE by combining SCADA and PMU data to create a fully-observed node feature matrix, which is a requirement for GNNs [3]}.
However, a purely SCADA-based state estimator or a SCADA-PMU hybrid state estimator does not have the advantages of a PMU-only state estimator, namely, time-synchronized outputs at high speeds.
Recently, a PMU-only framework has been presented in [4]}, which used factor graph-based GNN models for performing SE.
However, the measurement noise was assumed to be Gaussian in [4]}, and the impact of topology changes was not analyzed.
